On 17 December Hirvonen was officially announced as number one BP-Ford Abu Dhabi factory driver for the 2008 season, after Marcus Grönholm's retirement.[1] His young compatriot Jari-Matti Latvala was named Hirvonen's teammate in the second factory Focus.[1] Hirvonen started the season with a second place at the 2008 Monte Carlo Rally, which was Hirvonens and BP-Ford Team's target.[2][3] In Sweden he was considered favourite,[4] but had to settle for second being unable to keep up with his younger teammate's pace.[5] After Rally Mexico, where he had punctures and had to change a wheel, and in Rally Argentina, where he retired from the lead and then re-joined under SupeRally rules to take fifth place, Hirvonen took his first win of the season at the inaugural Jordan Rally.

Hirvonen took his second victory of the season in Turkey. Despite being the favourite to win at his home event, the Rally Finland, he could not match the pace of his title rival Loeb and finished a close second. In New Zealand, Hirvonen was leading when he had a puncture and a spin on the penultimate stage, dropping him to third behind the Citroën drivers Loeb and Dani Sordo. The stage was a disaster for Ford as Hirvonen's team-mate Latvala and Stobart M-Sport Ford driver François Duval both crashed out from second and fifth place, respectively.[6] Hirvonen then dropped eight points behind Loeb in the drivers' championship with only four more rallies to go.

Loeb soon secured his number one spot in the drivers' championship in Japan, but the manufacturers' title fight was still open as Ford trailed Citroën by eleven points. That changed when Hirvonen rolled his car onto its roof in stage five of the season-ending Wales Rally GB.[7] He was bumped down to 44th as a result, and managed to climb back up to eighth place by the end of the rally. This result meant that Hirvonen and co-driver Lehtinen become the first WRC drivers ever to score points on every round of a season.[8]

Hirvonen started the 2009 season with a third place behind the Citroën duo at the Rally Ireland. At the Rally Norway, which he won in 2007, he narrowly lost the win to Loeb after a tight three-day battle. He went to finish second to Loeb also in the following two rallies in Cyprus and Portugal. In Portugal, Hirvonen tied the record for the longest points finish streak in the series (22 events) with his former teammate Marcus Grönholm.[9] In the next round in Argentina, Hirvonen was six seconds behind Loeb after 14 stages when his Focus RS WRC incurred an engine problem.[10] His retirement saw Loeb take a 20-point lead over him in the drivers' standings.

At the Rally d'Italia Sardegna, Hirvonen and Loeb both dropped time on day one in a bid to gain a better road position. After Loeb incurred a puncture, Hirvonen found himself unable to catch teammate Latvala, who had been pushing in front from start to finish.[11] In the following Acropolis Rally in Greece, Hirvonen took his first win of the season. With Loeb crashing out, he reduced the Frenchman's championship lead to seven points.[12] At the following Rally Poland, Loeb crashed again, although recovered to seventh, with Hirvonen winning his second consecutive rally he moved to the top of the standings. In Finland, Hirvonen took the lead on the first proper stage and continued pulling away from Loeb to take his debut win in his home event.[13] A few weeks later, in Australia, Mikko was again in a tight battle with Loeb, where Loeb eventually won. Unfortunately for Loeb his car was found to have rollbar irregularities, as did Dani Sordo and Sébastien Ogier. They were then given 1 minute time penalties, which handed Hirvonen the win and 10 points. Hirvonen led the 2009 Championship by a point from Sebastien Loeb, and needing a win to clinch the title, but a hard landing from a jump on the penultimate stage caused the bonnet hinge to fail, as time ticked by to get rid of the bonnet cover, the Championship was handed to Loeb.[14]

In 2010 Hirvonen continued his partnership with Ford for the last time with the Ford Focus RS WRC before switching in 2011 for the new of 1.6 Ecoboost Ford Fiesta RS WRC. For 2012 Hirvonen Changes his seat for the Citroën DS3 WRC and he'll be partnering Sebastien Loeb for the Citroën Total World Rally Team.

His first rally win for Citroën was the fourth rally of the 2012 season in Portugal to provisionally take the lead in the championship, but he was later disqualified from the event due to irregularities with the clutch and turbo in his Citroën DS3 WRC.

2013 was a disappointing year for Hirvonen, finishing on the podium just five times, collecting no wins. He ended the season with one of his biggest accidents ever in Wales. He finished the season in 4th place.